It has been known for some time that lucanthone (I) and its metabolite, hycanthone (II) are active antitumor agents in mice with L-1210 and that the antitumor activity of both of these thioxanthenones was abolished by co-administration of a microsomal inhibitor. On the basis of our previous studies and some preliminary results it is postulated that I and II are biotransformed by the host to 1-(2-diethylaminoethyl)amino-7-hydroxy-4-hydroxymethylthioxanthenone (III) which then intercalates into DNA. This complex is then phosphorylated to give a phosphate ester of III while still intercalated. The ester acts as an alkylating agent to form a covalent bond with the DNA. On the basis of this hypothesis we plan to prepare a variety of carbamates and phosphates of II and III to determine their antitumor activity and the association constants of DNA complexes of a selected group of these esters. Their NMR spectra will be run and analyzed to determine whether covalent binding had occurred and if so the locus of the binding site. We also plan to investigate whether the binding to DNA of II and III is enhanced by incubation with microsomes or ATP at 37 degrees and whether certain esters of II and III will bind to DNA without the use of microsomes or ATP. A similar investigation will be carried out on 1-dialkylaminoalkylamino-4-hydroxy methyl xanthenones and some of its carbamate and phosphate esters.